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Numerical study on influence of protrusion heights on Reynolds stress and viscous stress variations in turbulent vortical structures

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Chinese Journal of Aeronautics 2024年第9期37卷 59-71页

作者： Zhiping LI Long HE Jingsai ZHOU Yueren ZUO Yao YIN Peng ZHANG Bo MENG Research institute of Aero-Engine Beihang UniversityBeijing 100191China School of Energy and Power Engineering Beihang UniversityBejing 100191China institute of Acoustics Chinese Academy of SciencesBeijing 100190China College of Aeronautical Engineering Civil Aviation University of ChinaTianjin 300300China AECC Hunan aviation Powerplant Research institute Zhuzhou 412002China

Analysing the influence mechanism of the riblet protrusion height on turbulent drag components is more beneficial in organising the vortical structure over the riblet ***, the Large Eddy Simulation(LES) is used to investigate the vortex structure over the riblet surface with different protrusion heights. Then, the variations of Reynolds stress and viscous shear stress in a turbulent channel are analysed. As a result, the drag reduction rate increases from3.4% when the riblets are completely submerged in the turbulent boundary layer to 7.9% when the protrusion height is 11.2. Further analysis shows that the protrusion height affects the streamwise vortices and the normal diffusivity of spanwise and normal vortices, thus driving the variation of Reynolds stress. Compared with the smooth surface, the vorticity strength and the number of streamwise vortices are weakened near the wall but increase in the logarithmic layer with increased protrusion height. Meanwhile, the normal diffusivity of spanwise vorticity decreases with the increase of protrusion height, and the normal diffusivity of normal vorticity is the smallest when the protrusion height is 11.2. Moreover, the protrusion height affects the velocity gradient of the riblet tip and riblet valley, thus driving the variation of viscous shear stress. With the increase of protrusion height, the velocity gradient of the riblet tip increases dramatically but decreases in the riblet valley.

关键词： Riblet Dragreduction Protrusion height Vortical structure Vortexdiffusivity Reynolds stress Viscous stress

Investigation of solids segregation of binary mixtures in a rotating drum at various Froude numbers

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Journal of Harbin institute of Technology(New Series) 2010年第5期17卷 701-705页

作者：何玉荣门玉宾刘元春刘文铁 School of Energy Science & Engineering Harbin Institute of Technology Shenyang Aeroengine Research institute Aviation Industry Corporation of China

To investigate the effect of the Froude number(Fr)on solid segregation in a rotating drum,a two dimensional mathematical modelling on solids behaviour in horizontally oriented rotating drums operated in rolling,cascading and cataracting modes has been carried out by using Euler-Euler multi-fluid model in Fluent6.2 *** particles and big particles are used in the work as binary mixtures to investigate segregation *** effect of Froude number(rotating velocity)on the flow field is *** is found that the model captures the main features of solids motion and segregation in the drum and numerical results agree well with limited experimental data for solid velocity.

关键词： Solids segregation binary mixture rotating drum Froude number numerical simulation

New time-“frequency rate” distribution for polynomial phase signal

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Journal of Harbin institute of Technology(New Series) 2010年第6期17卷 880-883页

作者：张云姜义成王勇刘瑞华 institute of Electronic Engineering Technology Harbin Institute of Technology College of Electronic Information Engineering Civil Aviation University of China

Time-"frequency rate" distribution(TFRD)is an extension of the traditional time-frequency distribution(TFD),and it exploits the relationship between time and frequency rate,or the second order phase derivative of signal.A new TFRD highly concentrated along the frequency rate of polynomial phase signal(PPS)is presented,which provides a new way to *** has been defined by introducing signal with a complex argument in the time-"frequency rate" analysis,and the inner interferences caused by the nonlinearity of the signal's phase can be reduced greatly with high time-frequency *** of the TFRD is discussed and the results are demonstrated by the application for accelerated target imaging of synthetic aperture radar(SAR).

关键词： TFRD PPS Complex argument synthetic aperture radar

Visual Localization in Urban Area Using Orthogonal Building Boundaries and a GIS Database

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机器人 2012年第5期34卷 604-613,619页

作者： LI Haifeng LIU Jingtai LU Xiang Civil aviation University of China Tianjin 300300 China institute of Robotics and Automatic Information System Nankai University Tianjin 300071 China

A framework is presented for robustly estimating the location of a mobile robot in urban areas based on images extracted from a monocular onboard camera, given a 2D map with building outlines with neither 3D geometric information nor appearance data. The proposed method firstly reconstructs a set of vertical planes by sampling and clustering vertical lines from the image with random sample consensus (RANSAC), using the derived 1D homographies to inform the planar model. Then, an optimal autonomous localization algorithm based on the 2D building boundary map is proposed. The physical experiments are carried out to validate the robustness and accuracy of our localization approach.

关键词：机器人设计人工智能信息处理

Novel approach for active vibration control of a flexible missile

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Defence Technology（防务技术） 2020年第4期16卷 956-967页

作者： Cheng-long Pan Ji-li Rong Tian-fu Xu Da-lin Xiang School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Norinco Group aviation Ammunition Research institute Harbin 150030China Beijing institute of Astronautical Systems Engineering Beijing 100076China

This paper investigates the feasibility of using an active dynamic vibration absorber(ADVA) for active vibration control of a flexible missile system through *** on the principles of a dynamic vibration absorber(DVA),a ring-type ADVA is first designed to attenuate the elastic vibration of the flexible missile,and the design of the active controller adopts the proportional-integral-derivative(PID)control *** motion equations of a flexible missile with an ADVA,which is subjected to follower thrust at its aft end,are derived using the Lagrangian *** the minimum of the root mean square(RMS) of the lateral displacement response of the center of mass as the objective function,a genetic algorithm(GA) is used to optimize the parameter of the DVA and PID *** numerical calculations show that the ADVA and DVA are effective in suppressing the vibration and provide approximately 41.2% and 17.6% improvement,respectively,compa red with the case of no DVA,The ADVA has better performance than the DVA,When the missile is subjected to follower thrust,the effect of vibration reduction is more effective than the case without follower *** is feasible to reduce vibration and improve the stability of flexible missiles by means of the ADVA.

关键词： Flexible missile PID controller Active dynamic vibration absorber Genetic algorithms

A serialized civil aircraft R&D cost estimation model considering commonality based on BP algorithm

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Chinese Journal of Aeronautics 2022年第4期35卷 253-265页

作者： Yongjie ZHANG Kang CAO Ke LIANG Yongqi ZENG Wenjun DONG School of aviation.Northwestern Polytechnical University Xi'an 710072China Shanghai Aircraft Design and Research institute Shanghai 201210China

The common design of serial civil aircraft, an important strategy of modern civil aircraft research and develop-ment, minimizes the whole life cycle cost of civil aircraft through asset reuse and resource sharing. However, the existing estimating model for the R&D cost of civil aircraft ignores the effects of common design, so the value estimated by estimating derivative models is significantly inconsistent with the actual one. To solve this problem, a novel assessment method for civil aircraft commonality indicators is developed based on fuzzy set in the present study, exploiting the attributes and structural parameters of the aircraft to be assessed as input to determine the degree of membership that pertains to the commonality sub-interval as the commonality *** the BP(Back Propagation) neural network algorithm is adopted to establish the relationship between the common index and the decrease rate of the R&D cost of derivative models. The model employs over a dozen typical civil aircraft models(e.g., Boeing, Airbus, and Bombardier) as the sample data for network learning training to build a mature neural network model for estimating the R&D cost of novel derivative models. As revealed from the comparative analysis on the calculated results of the samples, the estimated results of the model given the effects of commonality in the present study exhibit higher estimation accuracy and value for future work.

关键词： BP algorithm Civil aircraft R&D cost Common indicators Fuzzy set Serialized civil aircraft

Construction of compressed sensing matrices based on affine symplectic space over finite fields

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The Journal of China Universities of Posts and Telecommunications 2018年第6期25卷 74-80页

作者： Wang Gang Niu Minyao Fu Fangwei Chern institute of Mathematics and Lab of Pure Mathematics and Combinatorics Nankai University College of Science Civil Aviation University of China

The compressed sensing matrices based on affine symplectic space are constructed. Meanwhile, a comparison is made with the compressed sensing matrices constructed by DeVore based on polynomials over finite fields. Moreover, we merge our binary matrices with other low coherence matrices such as Hadamard matrices and discrete fourier transform(DFT) matrices using the embedding operation. In the numerical simulations, our matrices and modified matrices are superior to Gaussian matrices and DeVore’s matrices in the performance of recovering original signals.

关键词： compressed sensing coherence sparsity affine symplectic space finite fields

A Test Method for the Static/Moving State of Targets Applied to Airport Surface Surveillance MLAT System

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Transactions of Nanjing University of Aeronautics and Astronautics 2016年第4期33卷 425-432页

作者： Huang Rongshun Peng We Li Jing Wu Honggang Li Xingbo The Second Research institute of Civil aviation Administration of China College of Electronic Engineering University of Electronic Science and Technology of China

Due to the particularity of its location algorithm,there are some unique difficulties and features regarding the test of target motion states of multilateration(MLAT)system for airport surface *** paper proposed a test method applicable for the airport surface surveillance MLAT system,which can effectively determine whether the target is static or moving at a certain *** a normalized test statistic designed in the sliding data window,the proposed method not only eliminates the impact of geometry Dilution of precision(GDOP)effectively,but also transforms the test of different motion states into the test of different probability density ***,by adjusting the size of the sliding window,it can fulfill different test performance *** method was developed through strict theoretical extrapolation and performance analysis,and simulations results verified its correctness and effectiveness.

关键词： multilateration(MLAT) hypothesis testing motion state detection sliding window geometric Dilution of precision(GDOP)

ON RESIDUAL COMPRESSIVE STRENGTH PREDICTION OF COMPOSITE SANDWICH PANELS AFTER LOW-VELOCITY IMPACT DAMAGE

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Acta Mechanica Solida Sinica 2006年第1期19卷 9-17页

作者： Xie Zonghong Anthony J. Vizzini Tang Qingru College of Astronautics Northwestern Polytechnical University Xi＇an 710072 China Department of Aerospace Engineering Mississippi State University MS 39762 USA aviation Engineering institute Civil Aviation Flight University of China Guanghan 618307 China

This paper introduces a nonlinear finite element analysis on damage propagation behavior of composite sandwich panels under in-plane uniaxial quasi-static compression after a low velocity impact. The major damage modes due to the impact, including the residual indentation on the impacted facesheet, the initially crushed core under the impacted area, and the delamination are incorporated into the model. A consequential core crushing mechanism is incorporated into the analysis by using an element deactivation technique. Damage propagation behavior, which corresponds to those observed in sandwich compression after impact （SCAI） tests, has been successfully captured in the numerical simulation. The critical far field stress corresponding to the onset of damage propagation at specified critical locations near the damage zone are captured successfully. They show a good correlation with experimental data. These values can be used to effectively predict the residual compressive strength of low-velocity impact damaged composite sandwich panels.

关键词： sandwich structures impact delamination damage growth honeycomb core finite element method